U.S. patent application number 12/666886 was filed with the patent office on 2010-07-22 for method for detecting the direction of travel of a motor vehicle.
This patent application is currently assigned to Continental Teves AG & Co., oHG. Invention is credited to Daniel Fischer, Martin Grie er, Markus Irth, Andreas Kobe, Frank Schreiner, Christian Su mann.
Application Number | 20100185361 12/666886 |
Document ID | / |
Family ID | 39709361 |
Filed Date | 2010-07-22 |
United States Patent
Application |
20100185361 |
Kind Code |
A1 |
Irth; Markus ; et
al. |
July 22, 2010 |
METHOD FOR DETECTING THE DIRECTION OF TRAVEL OF A MOTOR VEHICLE
Abstract
A method for detecting the direction of travel or for detecting
a change in the direction of travel of a motor vehicle which has at
least two wheel speed sensor arrangements which each comprise an
encoder with an incremental scale and a plurality of scale
graduations and a wheel speed sensor (SEa, SEb, SEc, SEd) and are
connected to an electronic control unit, wherein, when a scale
graduation is sensed the wheel speed sensors each transmit a speed
signal to the electronic control unit, wherein the direction of
travel or a change in the direction of travel is identified at
least from the order in which the speed signals occur with respect
to the individual wheel speed sensor arrangements. A computer
program product for carrying out all the steps of the method is
also disclosed.
Inventors: |
Irth; Markus; (Mainz-Kastel,
DE) ; Grie er; Martin; (Eschborn, DE) ; Kobe;
Andreas; (Bensheim, DE) ; Schreiner; Frank;
(Friedrichsdorf, DE) ; Su mann; Christian;
(Oberursel, DE) ; Fischer; Daniel; (Schwalbach,
DE) |
Correspondence
Address: |
RATNERPRESTIA
P.O. BOX 980
VALLEY FORGE
PA
19482
US
|
Assignee: |
Continental Teves AG & Co.,
oHG
Frankfurt
DE
|
Family ID: |
39709361 |
Appl. No.: |
12/666886 |
Filed: |
June 2, 2008 |
PCT Filed: |
June 2, 2008 |
PCT NO: |
PCT/EP08/56791 |
371 Date: |
December 28, 2009 |
Current U.S.
Class: |
701/29.2 |
Current CPC
Class: |
B60W 40/10 20130101;
B60W 2520/06 20130101; G01P 13/04 20130101; G01P 13/045 20130101;
G01P 3/481 20130101 |
Class at
Publication: |
701/34 ; 701/29;
701/35 |
International
Class: |
G06F 7/00 20060101
G06F007/00; G01P 13/04 20060101 G01P013/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 29, 2007 |
DE |
10 2007 030 431.7 |
Claims
1.-11. (canceled)
12. A method for detecting a direction of travel or for detecting a
change in the direction of travel of a motor vehicle which has at
least two wheel speed sensor arrangements which each comprise an
encoder with an incremental scale and a plurality of scale
graduations and a wheel speed sensor and are connected to an
electronic control unit, transmitting a speed signal to the
electronic control unit when a scale graduation is sensed by each
wheel speed sensor, identifying the direction of travel or a change
in the direction of travel at least based upon an order in which
the speed signals occur with respect to individual wheel speed
sensor arrangements.
13. The method as claimed in claim 12 further comprising the step
of generating a sequence data record from an information item
relating to a chronological order in which the speed signals of the
individual wheel speed sensor arrangements successively occur.
14. The method as claimed in claim 13, wherein the sequence data
record comprises time stamp data which are respectively assigned to
a chronological occurrence of a speed signal of a wheel speed
sensor arrangement.
15. The method as claimed in claim 13, wherein when the direction
of travel or a change in the direction of travel is identified, the
sequence data record generated last is compared with at least one
preceding sequence data record.
16. The method as claimed in claim 13, wherein the following steps
are carried out in the course of an identification of a direction
of travel: generating a current sequence data record from the speed
signals received last in the electronic control unit, generating at
least one forward sequence data record, in which data are arranged
in accordance with forward travel, and at least one reverse
sequence data record, in which data are arranged in accordance with
reverse travel, from at least one preceding sequence data record
which is stored in the electronic control unit, comparing a current
sequence data record with both the at least one forward sequence
data record and with the at least one reverse sequence data record,
wherein, in each case, a correspondence characteristic variable of
the current sequence data record with the forward sequence data
record and the reverse sequence data record is calculated, and
carrying out a process for determining the direction of travel by
evaluating at least the two correspondence characteristic
variables.
17. The method as claimed in claim 16 further comprising the step
of calculating the correspondence characteristic variables by a
correlation calculation between the current sequence data record
and either the forward sequence data record or the reverse sequence
data record.
18. The method as claimed in claim 13 further comprising the step
of storing the sequence data record generated last in the
electronic control unit at defined times, continuously, or both at
defined times and continuously.
19. The method as claimed in claim 12, wherein when the direction
of travel is determined, at least one of the following additional
information items is taken into account: a velocity of the vehicle,
a transmission information item, a vehicle lighting information
item, a yaw rate of the motor vehicle, a lateral acceleration of
the motor vehicle, a steering angle information item, information
that a defined minimum velocity has been reached as an indication
of forward travel, or any combination thereof.
20. The method as claimed in claim 12, wherein a scale graduation
error characteristic variable is assigned to a plurality of the
scale graduations of the encoder of at least one wheel speed sensor
arrangement by evaluating the speed signals of the sensor in an
electronic control unit, wherein the direction of rotation of the
at least one encoder is identified from an order of the scale
graduation error characteristic variables which are assigned to
sensed scale graduations, after which a direction of rotation of
the one at least one encoder is taken into account in a
determination of the direction of travel of the motor vehicle.
21. The method as claimed in claim 12, wherein in the course of an
identification of a direction of rotation of at least one encoder,
scale graduation error characteristic variables are combined to
form a pattern which is respectively compared with a forward
rotation reference pattern and a reverse rotation reference
pattern, which reference patterns are formed directly or indirectly
from scale graduation error characteristic variables which are
stored in the electronic control unit, wherein, in each case, a
pattern correspondence characteristic variable of the pattern is
calculated with at least a portion of one of the two reference
patterns, after which the direction of rotation of this encoder is
determined from a comparison of the two pattern correspondence
characteristic variables, and the at least one identified encoder
direction of rotation is taken into account in the determination of
the direction of travel of the motor vehicle and/or is included in
the determination of the direction of travel.
22. A computer program product for carrying out the steps of the
method according to claim 12.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the U.S. national phase application of
PCT International Application No. PCT/EP2008/056791, filed Jun. 2,
2008, which claims priority to German Patent Application No. 10
2007 030 431.7, filed Jun. 29, 2007, the contents of such
applications being incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a method for detecting a direction
of travel or for detecting a change in the direction of travel of a
motor vehicle and to a computer program product for carrying out
all the steps of the method.
[0004] 2. Description of the Related Art
[0005] Document DE 40 38 284 A1 describes a method for identifying
the direction of rotation of an encoder, in which method the
encoder is encoded with different scale graduations, specifically
both large and small scale graduations. The rotational movements of
the encoder are sensed by a sensor. In the course of a rotational
movement of the encoder, the direction of rotation of the encoder
is identified from the signal pattern of the sensor which
correlates with the scale pattern of the encoder or the
chronological profile of the sensor signals. Such encoding of the
encoder is disadvantageous in that essentially integral multiples
of one revolution of the encoder have to be used to calculate the
speed of the encoder, as a result of which a speed measurement with
such an encoder provides relatively poor resolution.
[0006] In document DE 197 21 488 A1, a method for compensating
inaccuracies of a wheel speed sensor is proposed in which each
scale graduation is assigned a correction factor which is dependent
at least on the scale graduation error. This correction factor is
taken into account in the speed calculation.
[0007] Document DE 41 04 902 A1 describes a method for detecting a
direction of rotation in which, on the one hand, a composite signal
and, on the other hand, a difference signal are formed from the
output signals of two magnetic field sensor elements which are
arranged offset with respect to one another in relation to an
alternatingly magnetized encoder, and the direction of rotation of
the encoder is determined from these signals.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to propose a method
for detecting the direction of travel of a motor vehicle, wherein
in particular simple low-cost wheel speed sensor arrangements can
be used and/or a detection of the direction of travel can be
carried out at a relatively low velocity of the vehicle. Another
object of the invention is to propose a method which can identify
the direction of travel of a motor vehicle essentially directly
after the ignition has been activated and after a small distance
has been traveled.
[0009] The invention relates to the idea of identifying the
direction of travel and/or a change in the direction of travel from
the order in which a speed signal occurs with respect to the
individual wheel speed sensor arrangements of a motor vehicle.
[0010] A basic idea of the invention can preferably also be
described as follows:
The scale graduations of the encoders of the individual wheel speed
sensor arrangements of the motor vehicle are respectively sensed by
a wheel speed sensor. In this context, the respective specific,
relative orientation of the rotation between the encoder and wheel
speed sensor differs in each wheel speed sensor arrangement. In the
travel mode, the wheel speed sensor arrangements each have a
different rotational angle between the wheel speed sensor and the
next or the adjacent scale graduation which is to be sensed. The
pattern of these different encoder positions in relation to the
respective wheel speed sensor is mapped essentially by the order in
which these speed signals occur in relation to the individual wheel
speed sensor arrangements. Accordingly, the method according to
aspects of the invention expediently proposes identifying the
direction of travel or a change in the direction of travel of the
motor vehicle from this order.
[0011] The method according to aspects of the invention has the
advantage that the encoders in particular do not have to be encoded
specifically for the detection of a direction of rotation but
rather it is expediently possible to use commercially available
encoders with an incremental angle scale. In addition, the wheel
speed sensor preferably requires only one sensor element and no
additional signal processing unit for detecting the direction of
rotation, since the method is expediently used as a pure software
solution which requires only at least two incrementally measuring
low-cost wheel speed sensors. The method is suitable, in
particular, for detecting the direction of travel at low velocities
and in the case of short distances traveled, which are relevant to
the detection of the direction of travel.
[0012] A speed signal is expediently understood to be a
chronologically limited signal which is assigned to a scale
graduation which is sensed by the sensor, and said speed signal
comprises, in particular, a speed information item, and
particularly preferably the speed information item is encoded by
means of the duration of the speed signal. The speed signal very
particularly preferably has at least one speed pulse whose duration
is dependent on the speed or the rotational speed.
[0013] The term determination of the direction of travel or the
determination of the direction of travel is preferably also
implicitly understood to mean the detection of a possible change in
the direction of travel.
[0014] The wheel speed sensor is preferably an active sensor which
draws its energy in particular via its connecting lines to the
electronic control unit.
[0015] It is expedient that the wheel speed sensor has at least one
sensor element and a signal processing circuit. The sensor element
is preferably a magneto-electric transducer element such as an AMR
element, a GMR element, another magneto-resistive sensor element or
a Hall element.
[0016] An encoder is preferably understood to be a machine element
which has an incremental angle scale. It is possible both for, in
particular, ferromagnetic gearwheels or perforated disks, which in
combination with a permanent magnet generate a variable magnetic
airgap, to serve as encoders, and to be an integral sequence of
permanently magnetized north/south pole areas which form, in an
oscillating sequence, an encoder track which is particularly
preferably closed to form a circle and which is inserted, for
example, in a wheel bearing seal. The encoder serves very
particularly preferably as a pulse generator within the wheel speed
sensor arrangement.
[0017] It is expedient that a sequence data record is generated
from an information item relating to the chronological order in
which the speed signals of the individual wheel speed sensor
arrangements successively occur. Said sequence data record
comprises, in particular, time stamp data which are respectively
assigned to a chronological occurrence of a speed signal of a wheel
speed sensor arrangement. The chronological order in which the
speed signals occur can be acquired particularly easily and
precisely from the time stamp data. Furthermore, this data format
permits further processing of the data in the same way.
[0018] The sequence data record generated last is preferably stored
at defined times and/or continuously in the electronic control
unit.
[0019] When the direction of travel or a change in the direction of
travel is identified, the data record generated last or the current
data record is preferably compared with at least one preceding
sequence data record. The direction of travel can be identified
relatively precisely from this comparison, in particular if the
additional information as to which direction of travel this
preceding sequence data record is assigned is available. This
additional information is stored, in particular, additionally in
each sequence data record after the identification of the direction
of travel.
[0020] It is preferred that the following steps are carried out in
the course of an identification of a direction of travel: [0021] a
current sequence data record is generated from the speed signals
received last in the electronic control unit, [0022] at least one
forward sequence data record, in which the data are arranged in
accordance with forward travel, and at least one reverse sequence
data record, in which the data are arranged in accordance with
reverse travel, are generated from at least one preceding sequence
data record which is stored in the electronic control unit, [0023]
after which the current sequence data record is compared both with
the at least one forward sequence data record and with the at least
one reverse sequence data record, wherein in each case a
correspondence characteristic variable of the current sequence data
record with the at least one forward sequence data record and the
at least one reverse sequence data record is calculated, and [0024]
a process for determining the direction of travel is subsequently
carried out by evaluating at least one of these two correspondence
characteristic variables. In particular, the current sequence data
record is subsequently stored in the electronic control unit. The
direction of travel information which is determined last and which
is assigned to said sequence data record is particularly preferably
also stored in this sequence data record. The correspondence
characteristic variables are very particularly preferably each
calculated here by means of a correlation calculation between the
current sequence data record and the forward sequence data
record/reverse sequence data record.
[0025] When the direction of travel is determined, at least one of
the following additional information items is taken into
account:
The velocity of the vehicle, wherein in particular the information
that a defined minimum velocity is present is evaluated at least as
an indication of forward travel, a transmission information item,
in particular the information as to whether a forward gearspeed or
a reverse gearspeed is engaged, a vehicle lighting information
item, in particular the information as to whether the reverse light
is on, a yaw rate information item, a lateral acceleration
information item and/or a steering angle information item. This
permits the reliability of the method to be increased and the
plausibility of the identified direction of travel to be
estimated.
[0026] It is expedient that in addition in each case a scale
graduation error characteristic variable is assigned to a plurality
of these scale graduations of the encoder of at least one wheel
speed sensor arrangement by evaluating the speed signals of the
sensor in an electronic control unit, wherein the direction of
rotation of the at least one encoder is identified from the order
of the scale graduation error characteristic variables which are
assigned to the sensed scale graduations, after which at least this
direction of rotation of the at least one encoder is taken into
account in the determination of the direction of travel of the
motor vehicle. This essentially redundant detection of the
direction of travel permits the reliability of the entire method to
be considerably increased. In particular, in the course of an
identification of a direction of rotation of at least one encoder,
scale graduation error characteristic variables are combined to
form a pattern which is respectively compared with a forward
rotation reference pattern and a reverse rotation reference
pattern, which reference patterns are formed directly or indirectly
from scale graduation error characteristic variables which are
stored in the electronic control unit, wherein in each case a
pattern correspondence characteristic variable of the pattern is
calculated with at least a portion of one of the two reference
patterns. After this, the direction of rotation of this encoder is
determined from the comparison of the two pattern correspondence
characteristic variables, and this at least one identified encoder
direction of rotation is taken into account in the determination of
the direction of travel of the motor vehicle and/or is allowed to
be included in the determination of the direction of travel.
[0027] In the event of deactivation of the ignition of the motor
vehicle, at least the sequence data record generated last is stored
by the electronic control unit so that said sequence data record is
immediately available as information when the ignition is
activated. In particular, after the ignition of the motor vehicle
is activated, the sequence data record stored last is used by the
method.
[0028] The motor vehicle has, in addition to the wheel speed sensor
arrangements without detection of the direction of rotation,
preferably also or alternatively at least one wheel speed sensor
arrangement which can independently determine a direction of
rotation of its encoder and therefore essentially a direction of
travel. In particular, such a wheel speed sensor arrangement is
assigned to a wheel of a nondriven axle. The direction of rotation
information of this wheel speed sensor arrangement is particularly
preferably taken into account as essentially redundant
plausibility-checking information in order to increase the
reliability of the method during the calculation of the direction
of travel.
[0029] The method is expediently additionally carried out in order
to increase the reliability in motor vehicles which have other
means for determining the direction of travel such as, in
particular, wheel speed sensor arrangements for independently
detecting the direction of travel of the respective encoder.
[0030] The invention also relates to a computer program product for
carrying out all the method steps according to aspects of the
invention.
[0031] The method according to aspects of the invention is provided
for use in all types of motor vehicle, that is to say in
safety-critical systems which have at least one wheel speed sensor
arrangement. This preferably includes passenger cars, trucks, all
types of trailers and single-track motor vehicles such as motor
cycles. The use of the proposed method is appropriate in particular
if low-cost wheel speed sensors are used which cannot carry out
independent determination of a direction of rotation. It is
particularly preferably provided to use the method according to
aspects of the invention for detecting the direction of rotation
for an electronic parking aid.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Further preferred embodiments emerge from the following
descriptions of exemplary embodiments with reference to Figures, in
which, in a schematic illustration:
[0033] FIG. 1 shows an exemplary arrangement composed of four wheel
speed sensor arrangements of a motor vehicle, which illustrates the
different encoder positions,
[0034] FIG. 2 is a diagram of a method example for detecting the
direction of travel by evaluating the order of the speed signals,
and
[0035] FIG. 3 is an exemplary diagram of a method which has a
plurality of branches for the common identification of a direction
of travel.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] FIG. 1 illustrates by way of example four wheel speed sensor
arrangements 1a, 1b, 1c and 1d. These respectively comprise an
alternately magnetized encoder and a wheel speed sensor SEa, SEb,
SEc, SEd which senses the rotational movements of the encoder. The
relative orientation of the rotation .phi..sub.1, .phi..sub.2,
.phi..sub.3, .phi..sub.4 between the wheel speed sensor SEa, SEb,
SEc, SEd and the respective next scale graduation which is to be
sensed is respectively different in each wheel speed sensor
arrangement. This results in the individual wheel speed sensors
sensing a scale graduation at different times within the course of
the distance traveled by the motor vehicle, and as a result the
speed signals of the individual wheel speed sensor arrangements are
generated and transmitted to the electronic control unit ECU at
different times. The ECU determines the direction of travel or a
possible change in the direction of travel from the order in which
the speed signals occur with respect to the individual wheel speed
sensor arrangements.
[0037] FIG. 2 illustrates a method example by means of a diagram.
The speed signals of the wheel speed sensor arrangements 1a to 1d
are transmitted to the ECU and further processed there in function
blocks 10 and 20. In function block 10 a sequence data record,
which comprises time stamp data, is generated from the
chronological order in which the speed signals of the individual
wheel speed sensor arrangements occur. Function block 11 comprises
a stored preceding sequence data record and the information
relating to the direction of travel assigned to said sequence data
record. In each case, a forward sequence data record and a reverse
sequence data record are generated from this preceding sequence
data record in function block 12. Said sequence data records are
respectively compared in function block 13 with the current
sequence data record by means of a correlation calculation, wherein
in each case a correspondence characteristic variable, for example
a correlation coefficient, is calculated. These two correspondence
characteristic variables are evaluated in function block 14 in
order to determine the direction of travel. When the direction of
travel is determined, the result of a stationary state detection of
the function block 20, in which a possible stationary state of the
vehicle is detected from the speed signals, is also taken into
account here. The detection of the direction of travel of the
function block 14 can as a result identify a detected forward
travel or reverse travel or a stationary state of the vehicle or an
undefined travel state.
[0038] The undefined travel state can be identified on the basis of
insufficient verification of one of the three travel states
specified above.
[0039] The diagram shown in FIG. 3 illustrates a method example
which, based on FIG. 2, has additional method branches for
detecting the direction of travel of the motor vehicle. Within the
scope of the method example, the direction of travel of the motor
vehicle S5 is calculated from an input signal S1 which
incrementally makes available four counting signals from four wheel
speed sensor arrangements (not illustrated).
[0040] S1 is transmitted to function block 10 which determines the
chronological order in which the speed signals occur with respect
to the individual wheel speed sensor arrangements, for example
"RR.fwdarw.FL.fwdarw.FR.fwdarw.RL". In function block 11, the
order, for example containing the information
"RL.fwdarw.FR.fwdarw.FL.fwdarw.RR" in which the previous counting
signals of the individual wheel speed sensor arrangements occur is
stored in a memory. In function block 12 an order corresponding to
a forward direction of travel "RL.fwdarw.FR.fwdarw.FL.fwdarw.RR"
and an order corresponding to a reverse direction of travel
"RR.fwdarw.FL.fwdarw.FR.fwdarw.RL" are formed from this preceding
order. These two orders are compared with the order from function
block 11, that is to say the current order of the sensed counting
signals, in a function block 13. On the basis of these two
comparisons, a decision about the current direction of travel is
made in function block 14. This decision can result in a detected
forward direction of travel or reverse direction of travel and/or a
change in the direction of travel or an undefined detection. This
result of the detection of the direction of travel is transmitted
to function block 40. According to the example, a reverse direction
of travel is detected from the sensed order
"RR.fwdarw.FL.fwdarw.FR.fwdarw.RL" and the preceding order,
identical thereto, corresponding to a reverse direction of
travel.
[0041] The detection S3 of the direction of travel from function
block 5, which is identified subsequently, is also transmitted to
function block 40. In function block 2, a scale graduation error
characteristic variable is calculated from each speed signal which
is assigned to a sensed scale graduation wheel speed sensor
arrangement. Function block 2 makes available the four scale
graduation error characteristic variables of the speed signals of
all four wheel speed sensor arrangements. Said scale graduation
error characteristic variables are transmitted to function block 4
in which a pattern or a sequence of scale graduation error
characteristic variables is generated incrementally for the scale
graduation error characteristic variables of each encoder.
Furthermore, in each case a reference pattern for each wheel speed
sensor arrangement is stored in function block 3, wherein this
reference pattern comprises, for example, in each case a sequence
of scale graduation error characteristic variables assigned to all
the scale graduations of the corresponding encoder in the order of
a forward rotational movement of the encoder. These four reference
patterns are also transmitted to function block 4. In function
block 4, the four patterns are each correlated with the
corresponding reference pattern of the respective wheel speed
sensor arrangements, and the degree of correspondence is determined
by means of the calculation of a correspondence characteristic
variable between the pattern and the reference pattern. Here, in
each case the pattern with a forward rotation reference pattern and
a reverse rotation reference pattern which is arranged in a reverse
order are compared and in each case a correspondence characteristic
variable is calculated. In the event of one of the two
correspondence characteristic variables being greater, by a defined
relation, than the other correspondence characteristic variable and
having a defined minimum value characterizing the degree of
correspondence between the respective pattern and the reference
pattern, the direction of rotation corresponding to the reference
pattern is detected with the greater correspondence with the
pattern. If no direction of rotation can be detected, a further
scale graduation error characteristic variable is added to the
pattern and the previous method steps are repeated. If, in the
course of a common rotation of encoders a direction of rotation is
detected for each wheel speed sensor arrangement or its pattern in
function block 4, these directions S2 of rotation are transmitted
to function block 5, which comprises a detection of the direction
of travel of the motor vehicle on the basis of a majority decision
and makes available the direction of travel information S3 to
further functions of the motor vehicle control system and/or
systems of the motor vehicle.
[0042] In addition, within the scope of the exemplary method, the
scale graduation error characteristic variables of the function
block 2 are transmitted to a post-learning unit 6 in which the four
scale graduation error characteristic variables are filtered, with
the result that after transmission to function block 3, in which
the reference patterns or scale graduation error reference data for
all four wheel speed sensor arrangements are stored, they are
included in the reference data with a defined weighting.
[0043] In addition, by means of the four speed signals S1 in
function block 20, a detection of the stationary state is carried
out. The information relating to a possible stationary state of the
vehicle from function block 20 is also transmitted to function
block 40.
[0044] Furthermore, the method example comprises a method branch
with function block 30 in which additional information S4, for
example a transmission information item as to whether a forward
gearspeed or reverse gearspeed is engaged and a steering angle
information item are evaluated within the scope of a detection of
direction. For example, in addition, in particular within the scope
of an alternative example, the detection of direction is identified
from the yaw rate (.PSI.') and the lateral acceleration (a.sub.y)
or the yaw rate (.PSI.') and the steering angle. From the following
formula it is possible, in particular by ignoring the attitude
angle .beta., to infer the direction of travel by evaluating the
sign of the velocity which results from the formula:
v=a.sub.y*(.PSI.'+.beta.')=a.sub.y*.PSI.'
[0045] The result of this detection of direction is additionally
transmitted to function block 40.
[0046] In function block 40, a common evaluation of the direction
of travel information which is made available by the function
blocks 14, 5 and 30, and of the stationary state information from
block 20 is carried out. Here, a defined weighting of the
information is performed. At the output of function block 40, the
direction of travel S5 is made available, wherein this information
about the direction of travel has relatively high reliability and
plausibility. S5 is used, for example, at least as an input signal
for a parking aid system.
* * * * *